Contribution à l’étude des échanges convectifs en régime transitoire dans les Capteurs Solaires Plans à air ; Application au Séchage des produits agro-alimentaires.

Abstract

Solar air heaters can be used for many applications at low and moderate temperatures. There are different factors affecting the solar air heater efficiency, e.g. collector length, collector depth, type of absorber plate, glass cover plate, wind speed, etc. In this work we present an extensive comparative study on the thermal performance of various design of: single pass types of solar air heaters, SAHs: i) without obstacles, ii) with rectangular obstacles and iii) with a new form of obstacles (trapezoidal form) in the air flow duct. Thus, we have proceeded to the comparison of the best system with iiii) and double pass flat plate collector having the same type of obstacles in order to determine the best performing model. A theoretical model was constructed for all types of collectors, taking into account the new parameter, called the artificial roughness. Thus, we have proceeded to the application of these systems for the drying of agro alimentary products. We have sought to determine the drying kinetic for the forced convection. The drying air was heated by solar energy under variable outdoor conditions.